Conventionally, as build-up wear-resistant copper alloys, beryllium copper in which beryllium is added to copper, or precipitation-hardening type alloys, such as a copper-nickel-silicon alloy known as the Colson alloy, dispersion-strengthened type alloys in which hard oxide particles, such as Al2O3, TiO2 and ZrO2, are dispersed in copper-based matrices, have been known. However, the precipitation-hardening type alloys are such that the hardness degrades sharply at an age-hardening temperature (350-450° C.) or more, further, since the sizes of precipitated particles are very fine so that they are a few am or less, large wear might occur under frictional conditions accompanying sliding, even though the hardness is high. Moreover, although some of the dispersion-hardened type copper-based alloys which are obtained by internal oxidation methods maintain high strength and hardness even at high temperatures, it is hard to say that they are good in terms of the wear resistance because the dispersion particles are minimally fine. In addition, some of the dispersion-strengthened types which are obtained by sintering methods are not adequate to build-up applications because the metallic structures have been changed by fusion, though it is possible to control the sizes of the dispersion particles.
Hence, copper-based alloys of good wear resistance have been proposed recently (Patent Literature No. 1 and Patent Literature No. 2), in copper-based alloys in which particles having hard Co—Mo-based silicides (silicide) are dispersed in soft Cu—Ni-based matrices. Since they secure wear resistance by the hard particles and simultaneously secure toughness by the matrices, they are adequate to alloys for building up using a high-density energy source, such as a laser beam. However, when intending to further improve the wear resistance and heightening the area rate of the hard particles, the crack resistance during building up degrades, and the bead cracks occur often.
In order to solve this, the present inventors focused their attention on that Co—Mo-based silicide is hard and brittle, and developed a wear-resistant copper-based alloy, which can not only enhance the wear resistance in high-temperature regions but also can enhance the crack resistance and machinability, by decreasing Co—Mo-based silicide, by increasing the proportions of Fe—W-based silicide, Fe—Mo-based silicide and Fe—V-based silicide, which have properties of exhibiting lower hardness and slightly higher toughness than the Co—Mo-based silicide, by decreasing the Co content and Ni content, and by increasing the Fe content and Mo content.
Further, as a copper-based alloy powder for laser building up, one, which has a composition containing 10-40% nickel and 0.1-6% silicon, and simultaneously a sum of one member or two members or more selected from the group consisting of aluminum, yttrium, a misch metal, titanium, zirconium and hafnium being 0.01-0.1%, 0.01-0.1% oxygen, and the balance being copper and inevitable impurities, has been known (Patent Literature No. 3).
Furthermore, as a copper-based alloy powder for laser building up, one, which has a composition containing 10-40% nickel and 0.1-6% silicon, and simultaneously 20% or less cobalt, a sum of molybdenum and/or tungsten being 20% or less, 20% or less iron, 10% or less chromium, 0.5% or less boron, a sum of one member or two members or more selected from the group consisting of aluminum, yttrium, a misch metal, titanium, zirconium and hafnium being 0.01-0.1%, 0.01-0.1% oxygen, and the balance being copper and inevitable impurities, has been known (Patent Literature No. 3).
Patent Literature No. 1: Japanese Unexamined Patent Publication (KOKAI) No. 8-225,868
Patent Literature No. 2: Japanese Examined Patent Publication (KOKOKU) No. 7-17,978
Patent Literature No. 3: Japanese Unexamined Patent Publication (KOKAI) No. 4-131,341